Here's why: Because of the Criminal Justice Realignment Act of 2011, offenders in California sentenced to time in county jail are eligible to cut their sentences in half at an accelerated rate, as long as they behave. For every two days of actual time served, the defendant receives two days of actual time credit and two days of conduct credit -- for a total of four days of credit, or essentially half-time credit.

Still confused? In a nutshell: Serve two, get two -- as long as there aren't any incidents.

So in Brock Turner's case, he could get out in three months.

The provisions apply to inmates serving a misdemeanor sentence or felons, like Turner, sentenced to county jail as part of their probation.

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Most states grant good conduct credit, and anyone who works in or passes through the system likely knows about it.

When the judge in Turner's case announced he was inclined to sentence him to six months, Deputy District Attorney Alaleh Kianerci urged him to reconsider, noting that six months "really means three months in county jail."

California's formula has changed several times over the years. In 2011, it went to the current ratio and eliminated provisions that excluded inmates convicted of serious felonies, those required to register as sex offenders, or inmates with prior serious or violent felonies.

The change was intended to help alleviate overcrowding in California's jails and prisons, a problem that persists today.